Stereophonic sound and rerecording system



March 26, 1957 O. B. GUNBY STEREOFHONIC SOUND AND RERECORDING SYSTEM Filed May 29, 1953 States Patent O srERorHoNIC SOUND AND RERECORDING SYSTEM Olin B. Gunby, Los Angeles, Calif., assignor to Radio 4 This invention relates to motion picture sound systems, and particularly to a sound system for providing stereophonic and special sound effects. A

Standard motion picture thirty-tive millimeter film has two rows of perforations or sprocket holes, a wide picture area along one row of sprocket holes, and a narrow sound track area along the other row of sprocket holes. The present invention utilizes such a film with two additional tracks thereon, which are provided by a coating of magnetic particles between each row of sprocket holes and the edges of the fhn. With such a plurality of tracks, the iilm may be played in the normal type of projector when provision is made to accommodate the added thickness of the magnetic coatings, or may be used with special equipment where each magnetic track feeds a separate amplifying system connected to a speaker on either side of the screen. By the use of all three tracks, directional or stereophonic eiects may be obtained.

Another feature of Ithe invention is a system whereby the sound is recorded in a single track, as is now standard practice, which track may be rerecorded, during which operation, three separate tracks are recorded, the amplitudes of the new tracks varying in accordance with the position of the source of sound on the screen. That is, when the source of sound is at the right of the screen, that particular track will have an amplitude higher than the tracks feeding the other speakers. This type of recording has several advantages, such as avoiding complex, bulky, and expensive stereophonic recording equipment, and not requiring any personnel in addition -to that required for normal recording. Furthermore, the control of the stereophonic effect is placed in the hands of highly skilled personnel who have adequate facilities to work with. Also, the stereophonic effect desired can berehearsed until the results` are ask desired, which prevents possible costly delays inV the recording of the original sound. f A

. Theprincipal object of the invention, therefore, is` to facilitate the obtaining of stereophonic and special sound effects.

Another object of the invention is to provide a motion picture sound film suitable for single speaker presentation and also stereophonic sound presentation;

A further object of the invention is to provide a stereophonic sound system by rerecording from a single composite original track.

Although the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the appended claims, the manner lof its organization and the mode of its operation will be better understood by referring to the following description, read in conjunction with the accompanying drawings, forming a part hereof, in which:

Fig. l is a diagrammatic view of a system using a standard sound track and special magnetic tracks, and

Fig. 2 is a diagrammatic view of a system for rerecording stereophonic sound for the system of Fig. 1.

Referring now to Fig. l, a section of a film 5 has picicetures 6 thereon and a standard composite photographic sound track 7 positioned in the standard location between the lm perforations 9 and pictures 6. Between the perforations 9 and ltland the respective edges of the film 5, there are two magnetic tracks 12 and 13. As mentioned above, the gate of a projector is slightly modified to accommodate the extra thickness caused by the magnetic particles on which the magnetic tracks 12 and 13 are recorded. However, with this modication, the film 5 may be used in a standard projector in a theater which has a single channel system. In this instance, track 7 is connected to the single channel, as shown by the dotted line 14. This channel includes photographic reproducer 15, amplifier 16, and a center speaker 17 behind a screen 18.

However, should a theater be provided with two magnetic reproduce heads 21 and 22 and two associated re;V producing channels, tracks 12 and 13 are connected thereto, as shown by dot-ted linesp23 and 24, respectively. The channel for magnetic head 21 is shown including `an arnpliiier 26 feeding a loudspeaker 27 on the left-hand side of the screen, while the channel for magnetic reproduce head 22 is shown including .an amplifier 29 feeding a speaker 30' on the right-hand side of the screen. With this type of system, the sound in the photographic track 7 will beumixed during rerecording in the conventional manner for normal theater release. The magnetic track 12 connected to the left speaker 27 would contain those sounds giving the illusion of a sound source to the left of the screen. The sounds recorded on magnetic track 13 would include those sounds `giving the illusion of sound to the right of the screen.

Another arrangement would be to use one of the magnetic tracks as a control track in the manner disclosed and claimed in Kellogg U. S. Patent No. 2,499,587, or in any other standard system using band pass filters, variable gain amplifiers, and relays, which may be used to switch the sound source from any one speaker system to one or more of the other speaker systems and to vary the volume level in each speaker system. The control track could exercise this type of control on both the pho- Ito-graphic track and the other magnetic track. After such a film 5 has been used in the systems having a stereophonic sound system and is well worn from operation in de luxe theaters, and if it will thereafter only be projected in theaters having a single speaker, the mag netic tracks could be buifed oii or removed in some other suitable manner and it would not be necessary to change the gates in the projectors of these theaters. This provides complete utilization of the film before it is con- Sider-ed to be worn out.

Referring now to Fig. 2, .a rerecording system is shown with'a sound ilm reproducer'SZ reproducing an original composite track, such as is shown at 7 in Fig. l. The reproducer feeds an amplifier 33 and then adistribution network 34, which simply divides the signal into three channels 35, 36, and 37. In channel 35 is a variable attenuator pad 39 for varying the lever of the signal in this channel, while similar variable attenuator pads are shown at 41 and 42 in channels 36 and 37, respectively. The outputs of the three pads feed three respective switches 44, 45, and 46, which are mechanically interconnected as shown by the dotted line 47. When the switches are thrown to the left-hand position, switch 44 will connect the output of pad 39 to amplifier 49, which will feed the left speaker 50. Switch 4S, in its left-hand position, connects pad 41 to amplifier 52, which feeds the center speaker 53 behind screen 54. The left-hand position of switch 46 will connect pad 42 to amplifier 55 connected to right speaker 56. The switches are in the position just described during rehearsals. That is, the mixen or rerecording operator, will adjust the pads 39, 41, and

42 to increase the volume and/ or phase of the signal in the proper speaker in accordance with the source ot sound as it appears on thes'creen 54, which is projected thereon simultaneously with the sound reproduction.

YAfterrthe, operator has provided the proper leyels Yiin the three channels during rehearsals, the switches 447 45, and 46 are then thrown to their right-hand positions. Switch '44 now connects the output of pad 39 to an amplifier 58 feeding a recorder 59, which recorder may be a magnetic recorder recording track 12` of the. lm in Fig. l. Switch 45 now connects the output of pad 41 to an amplifier 61 feeding a photographic recorder 62, which may produce track '7, shown on hlm 5. The switch 46 now connects the output of pad- 42 to an amplier 64 feedingI a recorder 65, whichmay Vbe a magnetic Arecorder recordingy track 13 on film 5. Recorder 62 may also be a magnetic recorder, so that it a take is spoiled', `the recording can be erased and another one made. After a satisfactory take has been made, it can then be transfer/red to a photographic track for subsequent printing of film 5 to produce track 7.

This rerecording system, therefore, permits the original recording to be accomplished in the normal manner without the multiple sound recording systems required for stereophonic recording. Also, the normal amount of personnel is required. However, during the rerecording operation, the highly skilled mixers will shift the level of the sounds in the three channels, particularly channels 35 and 37, in accordance with the position of the source of sound on the screen 54. Thus, the hlm 5 may be originally recorded stereophonically or produced with the rerecording system shown inFig. 2.

l claim:

l. A rerecording system comprisingy a reproducer of a single sound track, a distribution network connected to said reprcducer for feeding three channels with the signal from said single sound track, a variable attenuation pad in each of said channels, switches connected to the outputs of, said respective pads, a loud speaker at a certain position with respect to a picture screen, a second loud speaker at another position with respect to said screen, a third loud speaker at a third position with respect to said screen, and a sound recorder for each of said channels, said switches in one position connecting the output of each of said pads to respective speakers, and said switches in another position connecting the output of each of said pads to respective recorders.

2. A rerecording system in accordance with claim l, in which the recorder connected to the switch connectable to said first mentioned loudspeaker is a photographic track recorder, and the other of said recorders are magnetic track recorders.

3. A rerecording system for rerecording from a single sound record to a plurality of sound records comprising a reproducing channel for said single record, said record containing all the sounds produced by objects ink a picture adopted` to beprojected on a screen, a plurality of transmission channels, means or simultaneously impressing said reproduced single sound record on said plurality of channels, said channels including a corresponding plurality of loudspeakers adjacent said screen, means in said channels for shifting the level of the signals in said loudspeakers to correspond with the position of objects shown on said screen with respect to said speakers, means for separately recording the output of each of said channels, and means for connecting said' lei/el shifting means to said loud speakers and said recording means at mutually exclusive times.

4. A rerecording system inl accordance with claim 3, in which said means for impressing said reproduced single record on said plurality of channels is a distribution network connectedbetween said:v reproducing channel and said plurality of channels.

5. A rerecording system in accordance with claim 3, in which said recordingrneans. a recorder in each of said channels andl said. Vlast-rn'entioned means is a twoposition switch in each of said ehannels.

6. A rerecording system for rerecording from a single sound record to a plurality of soundecords comprising a reproducer of said single sound. record,y a. plurality of sound current transmission channels, a distribution network interconnecting saidreproducer and said plurality of sound current transmission chan'nels., said distribution network being adapted to-simultaneously fee-d said plurality of channelswith said reproduced single sound record, a variable attenuation pad in each of said channels, a plurality ofl speakers spatially disposed with respect to each other, said speakers corresponding in number to the number of said channels, sound recorders corresponding in number to the number of said channels, and switches adapted to connect each of said attenuation pads to a speaker and a recorder, one position of said switches connecting said attenuation padsv to said speakers and another position of said switches connecting said attenuation pads to said recorders. Y

7. A rerecording system in accordance with claim 6 in which said recorder corresponding to a centrally disposed speaker is a photographic recorder andv said other recorders are magnetic recorders.

References Cited inthe tile of thispatent UNITED' STATES PATENTS France ..L. Oct. 31, 1951 

